Treatment of cellulosic fabrics

ABSTRACT

CELLULOSIC FABRICS ARE PROVIDED WITH CREASE RESISTANCE AND HIGH WASH AND WEAR RATINGS BY PADDING THE FABRIC IN A SOLUTION CONTAINING 5-15 WT. PERCENT OF A CELLULOSE REACTANT TYPE CROSS-LINKIG AGENT AND 5-20 WT, PERCENT OF NH4CI OR NH7NO3 AND CURING THE PADDED FABRIC AT 110* 140* C. FOR 1-8 MINUTES.

United States Patent U.S. Cl. 8116.3 8 Claims ABSTRACT OF THE DISCLOSURE Cellulosic fabrics are provided with crease resistance and high wash and wear ratings by padding the fabric in a solution containing 5-15 wt. percent of a cellulose reactant type cross-linking agent and 5-20 wt. percent of -NH.,Cl or NH NO and curing the padded fabric at 110- 140 C. for l8 minutes.

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of application Ser. No. 818,199 filed Apr. 21, 1969, now abandoned, which is a streamlined continuation of application Ser. No. 405,230, filed Oct. 20, 1964 and now abandoned. This application claims priority based on application filed in Japan on Oct. 21, 1963; Dec. 18, 1963 and Dec. 20, 1963.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to methods for providing fabrics made of cellulosic fibers with improved crease resistance and good wash and wear ratings without impairing their mechanical properties.

Prior art As a result of the low dry crease recovery, fabrics made of cellulosic fibers generally have a great deal of creases and do not readily return to their original state when they are in wear. Further, on account of the low wet crease recovery, these fabrics require ironing after ordinary domestic washing and their wash and wear ratings are not good. There have been many attempts proposed to improve upon these drawbacks. Some of the proposed methods have succeeded in making fabrics recover from the creased state in wear to their original state but none of them have been satisfactory in providing fabrics with good wash and wear ratings. In order to obtain fabrics resistant to crease and also possessing good wash and wear ratings, both the dry crease recovery and the wet crease recovery must be elevated to appropriate values.

The wet crease recovery of fabrics can be elevated by subjecting cellulosic fibers to a cross-linking treatment in the swollen state with a bi-functional or multi-functional cross-linking agent, but the dry crease recovery shows hardly any change with such a treatment. Accordingly it is possible to obtain fabrics which can only be creased with difficulty in wear and possessing good wash and wear ratings by combining the wet state cross-linking treatment and the conventional dry state cross-linking treatment. However this method requires a two step treatment and accordingly is not commercially attractive. Moreover it has a drawback in that the strength of the treated fabrics obtained is greatly impaired.

An object of the present invention is, accordingly toprovide methods for simultaneously improving both the dryand the wet-crease recovery of cellulosic fabrics by a one step treatment. Another object of the present invention is to provide methods for economically manufacturing cellulosic fabrics possessing crease-resistance and good wash and wear ratings.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, cellulosic fabrics are subjected to padding in a solution containing a reagent capable of cross-linking with cellulose by an acidic catalyst in a concentration such that the fabrics contain from 5 to 15% of the reagent based upon the weight of cellulose,

. and as a catalyst, a large amount, i.e., 5-20 wt. percent of ammonium chloride or ammonium nitrate. The padded fabrics are then subjected to curing. In the present invention the amount of catalyst used is extremely large, compared with common methods, namely, it amounts to from 5 to 20% based upon the weight of cellulose in the fabric. Furthermore the curing of the present invention is carried out in two different ways. In the first method, the above treated cellulosic fabrics are cured in an atmosphere containing from 20 to by volume of moisture. In the second method, the above-treated cellulosic fabrics are subjected to press curing with the fabric being pressed and heated in a contactly closed passage by passing or holding same between two moving substances impermeable to steam. At least one of the two substances is a heated body.

The cross-linking agents used in the present invention are so called cellulose reactant type cross-linking agents which can react with cellulosic fabrics in the presence of an acidic catalyst, forming cross-linkages. They include dimethylol hydroxy ethylene urea, tetramethylol acetylene diurea, dimethylol urone, dimethylol ethylene urea, dimethylol propylene urea, dimethylol ethylene glycol, dimethylol adipic amide and the methyl and ethyl esters of all the foregoing compounds. Especially useful are dimethylol hydroxy ethylene urea and tetramethylol acetylene diurea and dimethylol urone is next in preference.

The catalysts used in the present invention are NH Cl and NH NO They have relatively strong acidity and show powerful catalytic action. The amount of catalyst used is in the range of from 5 to 20% based upon the weight of the cellulosic fibers. The strong catalysts such as NH Cl and NH NO are used in the prior art techniques in the range of from 0.1 to 0.4% based upon the weight of fabrics.

Compared with the conventional methods, the characteristic feature of the present invention lies in the use of large amounts, i.e. 10 times as much or more of the powerful acidic catalysts. As a result of this, the large amounts of salt cause the cellulose to swell and by their powerful catalytic action, the cross-linking can be effected even in the swollen state at low temperatures. Moisture in the cellulosic fabrics at the time of cross-linking or in the swollen state of the cellulosic fabrics is an extremely important factor. When the cross-linking is carried out in a perfectly dry state, the increase in wet crease recovery is relatively smaller than that of the dry crease recovery. When the cross-linking reaction is carried out in a perfectly wet state, the dry crease recovery does not increase and only the wet crease recovery is increased. When the moisture content in the fabrics at the time of cross-linking and the swollen state of cellulose are maintained at an appropriate value in carrying out cross-linking reaction, both the dry and wet crease resistance are increased at the same time, thereby providing the fabrics with desirable wash and wear ratings. These objects can be accomplished satisfactorily by the present invention. For example, when a powerful catalyst such as NH CI or NH NO' is used in an amount of from to based upon the weight of cellulose, and cellulose is left in the open air after a conventional preliminary low temperature drying, it is generally in a considerably swollen state due to the swelling eifect and the moisture absorbing effect of the salt with respect to cellulose. When curing is carired out at a low temperature, the reaction rapidly proceeds on account of powerful catalytic action of large amounts of NH Cl.

For the purpose of carrying out the cross-linking reaction while maintaining the swollen state of cellulose at the most preferable condition, the first curing method is preferable. In other words, the method of carrying out the curing of cellulosic fabrics in a steam containing atmosphere is most suitable. In this case the moisture content in the curing atmosphere is important. The moisture in the atmosphere increases the moisture in the fabrics as a result of which the wet crease recovery is improved. The moisture in the atmosphere must be over 20% preferably over 30% by volume. The more the atmospheric moisture content increase, the greater the moisture in the fabrics, accordingly, the Wet crease recovery tends to increase. In this case, the curing temperature will be sufiicient when it is from 110 C. to 140 C. preferably from 120 C. to 130 C. for 2 to 4 minutes.

The second method of curing is an attempt in which a novel idea is further added to the other methods. It is generally considered to be necessary that both the dry and wet crease recovery be at the preferred value in order to obtain fabrics possessing good wash and wear ratings but the state of the fabrics at the time of cross-linking is also important. When the appearance of the fabrics at the time of cross-linking is not satisfactory, the cross linking is carried out in that state. Accordingly fabrics having both a good appearance and good wash and wear ratings cannot be obtained. This is the point to which one must pay most attention in producing wash and Wear fabrics.

In the second curing method, fabrics are held between two moving substances impermeable to steam, which form a contactly closed passage. The fabric is pressed and cured while passing through the passage. At least one side or both sides of the fabric is a heating body. In this case the moisture content of the fabric is a very important factor. That is, affording crease resistance and good wash and wear ratings to fabrics in one step, an ap ropriate moisture content of fabrics and swollen state of fabrics are extremely important. The moisture content of the fabrics is generally more than 12%, preferably in the range from 15 to When fabrics possessing such a moisture content are heated by the present method, a part of the moisture evaporates, but since the fabrics are tightly confined in and pressed by steam-impermeable surfaces at both sides, a considerable amount of nonvolatile moisture remeans trapped in the fabrics. When the curing is carried out by such a method, cellulosic fabrics, in a relatively swollen state are pressed by solid and completely fiat surfaces from both sides and the cross-linking reaction is carried out at the state in which the appearance and shape of fabrics are properly maintained. By such a shaping effect, the crease resistance is further improved and the wash and wear ratings are substantially increased.

In carrying out this method, an apparatus consisting of a revolving metallic heating cylinder coated with heat and acid-resistant rubber, synthetic resin or the like; and an endless belt tightly contacting therewith and running at the same speed under a certain tension, and made of a heat-resistant synthetic rubber, silicon rubber or the like is suitable. The curing temperature is from 110 C. to 140 C. preferably from 120 C. to 135 C. Since the heating is efifected by the direct contact with a solid, the heating time can be shorter than the case in gaseous medium. Heating from 20 to 180 seconds, generally from to 60 seconds will be sufficient to achieve the purpose.

Cellulosic fibers useful in the present invention include natural cellulosic fibers such as cotton, hemp, ramie, and the like, regenerated cellulosic staple fibers and filaments 4 such as viscose rayon, cupra rayon, fortisan and the like. Mixtures of these with other synthetic fibers, mixed spun, mixed woven and mixed twisted products are also useful.

EXAMPLE 1 Plain fabrics made of cupra-rayon filament yarns (Warp 60 den. Filling den.) were padded in a solution containing 15% dimethylol hydroxyethylene urea and 10% NH Cl. Amounts of pick up were about After being predried at a temperature of 60 C. for 3 minutes, the fabrics were subjected to three kinds of curing; (i) in the dry atmosphere at a temperature of C. for 2 minutes 30 seconds. For comparison purposes (ii) in an atmosphere containing 40% by volume of moisture at a temperature of 130 C. for 2 minutes 30 seconds. (iii) by clamping with a metallic cylinder and a rubber belt at the state of moisture equilibrium and pressing at a temperature of 130 C. for one minute.

For the purpose of comparison, the same fabrics were padded in a solution containing 15% of dimethylol hydroxyethylene urea, and 1% of Zn(NO and after being predied, subjected to curing (iv) at a temperature of C. for 3 minutes in a hot wind circulating type heating apparatus. The resulting fabrics were then subjected to soaping and drying to obtain finished products. Properties of the resulting fabrics are shown in Table 1.

l D.O.R. (Dry crease recovery) and W.C.R. (Wet crease recovery) are expressed in the percentage of recovery measured at. 5 minutes after a procedure consistin of orthogonally twice-folding a. specimen having a width of 10 mm. an a length of 40 mm. applying 500 g. of load for 5 minutes and removing the load.

a F.A. (Flexlng abrasion resistance) is measured by employing a universal wear tester and specimens of 25 mm. while applying tensile loads of 2 lbs. and compression loads of 1 1b.

T.S. (Tearing strength) is measured by employing a commercial Ermendolf type tester having a pendulum weight of 2.3 kg. and a capacity of energy of from 0 to 13.7 kg./cm. and, specimens of 63 mm. length with carved length of 20 mm. and tear length of 43 mm.

4 W. 8: W. (Wash and wear rating) is measured according to AATCC Tentative Test Method 88-19611. Test specimens had a dimension of 15" x 15", Washing procedure-machine 41 0., Drying procedurc- Drip Evaluation procedure-Low angle.

It is seen that every one of methods (1), (ii) and (iii) improves the flexing abrasion resistance notably, the wet crease resistances are improved in the order of (i), (ii) and (iii) and the wash and wear ratings are also improved.

Comparative Example 1 Plain fabrics made of cupra rayon filament yarns (Warp 60 den. Filling 75 den.) were padded in a solution con taining 15% dimethylol hydroxyethylene urea and 8% of NH Cl and pre-dried. Amounts of pick up were 88%. Subsequently the curing was carried out in a dry atmosphere at a temperature of 130 C. for 2 minutes and 30 seconds. This is not one of the two methods of the present invention. Then, soaping and tentering were applied. The properties of the resulting fabrics are shown in Table 3. For the purpose of comparison, another curing was carried out by employing a solution containing 15% of dimethylol hydroxyethylene urea and 1% of salt of nitric acid at a temperature of 150 C. for 3 minutes. The properties of the treated fabrics are also shown in Table 3.

Comparative Examples 2-9 The conditions of treatment applied to fabrics by the same method as in Comparative Example 2 are shown in Table 2 and the properties of the resulting fabrics are shown in Table 3.

TABLE 2 C Processing material Catalyser Curing omparative example Amount Amount Tempera- Time number Name (percent) Name (percent) ture 0.) (min.) Specimen cloths 1 Dimethylolhydroxyethylene urea... 15 NH4C1 8 130 2.5 Cupra-rfargon filzlia m eigyarng p 8111 a T105 en. 15 Zn(NO3)2 1 150 3.0 Do. 15 NH4C1 15 130 2. 5 D0. 15 NHaCl 8 120 5. D0. 15 NH C1 8 140 1. D0. 15 NH C1 8 130 3. 0 D0. 15 NH C1 130 3. 0 D0. Zn(NOa)2 1 150 3. 0 D0. 15 NH4C1 10 130 3. 5 D0. 15 Zn(NOs)2 l 150 3. 0 Do. 15 61 10 130 3. 0 cupra plain fabrics, W.F. Control 10 15 Zn(NO3)z 1 150 3.0 D6. 9 Tetramethylol acetylene diurea 13 NH4C1 10 130 3.0 Viscose filamgrsig plain fabrics, Control -do 13 Zn(NO;)z 1 150 3.0 Do.

TABLE 3 Crease Flexing Wash and recovery abrasion Tearing wear Crease Fleklng Wash and (percent) resistance strength rating recovery abrasion Tearlng wear (percent) resistance strength rating Comparative Com arative Example 8:

Ex mple 1- W Z2 23? 3-3? 4 W 70 439 4 comp-11551651115551; F 69 276 0. 13 8 00 1; Comparglti e Example 'w 73 78 gg 34 W 62 385 0 70 4 it 2: 09 483 0 s0 C 64 298 0 4 omparatlve xamp e 70 305 0 74 9 control:

2 70 574 0.81 4 r F 61 21 0 53 as 308 0. 74 3a EXAMPLE 2 1 9 0.84 7 2 4 Plain fabrics made of cu ra ra on filament arms 70 24 0 7 Exam 1e (Warp 60 den. -F. 75 den.) were padded in a solutlon p 69 422 0 75) 4 40 containing 15% dimethylol hydroxyethylene urea and 68 237 M3 8% NH C1 and dried. Amounts of pick up were 86%. The curing Was carried out in an atmosphere containing F g? 333 8% 4 43% moisture (by volume) at a temperature of C. Comparative Example for 2 minutes and 30 seconds. Then, soaping and tenterw 70 161 0 78 ing were applied. The properties of the resulting fabrics FIIIIIIIIIIII 66 101 0172} 49 are shown in Table 4. Comparative Ewmple 7: 65 597 0 83 EXAMPLES 3-13 C :fIIIIII}: 64 366 0:74 4 The conditions of treatment applied to fabrics by the $15,12 .3 e same method as in Example 1 and Comparative Example g! g2 8 2 3 0O 1 are shown in Table 4 and the properties of the resulting fabrics are shown in Table 5.

TABLE 4.

Processing material Catalyser Moisture Tempera- Example Amount Amount ure Time number Name (percent) Name (percent) percent) C.) (min) Specimen cloths 2 Dimethylolhydroxyethylene urea 15 NILGI 8 43 130 2.5 Clfirgafilarvnelgdyalrn lplain a rics, 5 15 Zr1(NOa)2 1 0 150 3 D0. 15 NH4C1 15 21 130 27 5 D0. 15 NH4O1 10 62 130 3 Do. 15 NH4CI 20 63 130 3 D0. 15 NH4C1 10 91 130 3 D0. 15 NH4C1 10 61 2 D0. 15 NH4C1 15 45 120 5 DO. 10 NH4NO 10 53 130 3 Do. 15 NH1C1 10 53 130 3 D0. 15 Zn(NOs)z 1 0 3 D0. 15 H401 10 51 130 3. 5 D0. (1 15 Zn(NOa)2 1 0 150 3 D0. 12 Dimethylol hydroxyethylene urea. 15 NHlCl 10 62 130 3 spullizcgapa plain fabrics, Control .410 15 znmom 1 0 150 3 Do. 13 Tetramethylol acetylene diurea 13 NH4C1 1O 62 130 2.5 Viscose rayon 7plain fabrics, Control do 13 znomm 1 o 150 a Do.

TABLE Wash Dry Wet Flexlng and crease crease abrasion Tearing wear recovery recovery resistance strength rating (percent) (percent) (times) (kg.) (grade) Example 2:

72 64 429 0. 77 H 71 64 284 0. 76 Example Example 2; control: W 71 57 192 0. 73 34 73 67 351 0. 75 71 as 257 0. 72 i 70 56 169 0. 75 as 57 107 o. 72 i 73 60 327 0. 89 71 as 196 0.80 i

63 58 357 0.71 F 64 57 295 0. 55 i Example 13, control:

EXAMPLE 14 a silicon rubber belt under tension and running at the same speed as the perlpherical speed of the cylinder while being clamped by the cylinder and the belt. Then, soaping and tentering were applied. The properties of the resulting fabrics are shown in Table 7.

EXAMPLES 15-23 The conditions of treatment are applied to the fabrics by the same method as in Example 14 are shown in Table 6 and the properties of resulting fabrics are shown thin film of synthetic resin and an apparatus wound with in Table 7.

TABLE 8 Processing material Catalyse! Baking Example Amount Amount Tempera- Time number Name (percent) Name (percent) ture C.) (min) Specimen cloth 1'1. Dimethylol hydroxyethylene urea--. 15 NH4C1 10 1 Ci$rg0la1ema yarn plain fabrics Control. 15 Zn(N0:i)a 1 150 3 Do. 15 15 NHqCl 10 0.5 Do. 16 15 NH-iCl 10 120 3 Do. 17. 15 NHiCl 5 130 1% D0. 18- 15 NHaGl 20 130 -76 Do. 19 15 NHQC]. 13 130 1 D0. Control. 15 ZI1(N03)3 l 3 Do.

15 NH4C1 13 130 1 D0. Control- 15 Zn(NO3)2 1 150 3 Do. 21 15 NH4N03 13 130 1% Do. 22 15 NHaCl 10 130 1 D0. Control. o 15 Zn(N0a)z 1 150 3 Do. 23 Tetramethylol acetylene diurea 13 401 10 130 1 vi zsggseF rafiygn plain fabrics, W.- Control -110 12 21101092 1 150 a Db.

TABLE 7 Wash Flexing and Dry crease Wet crease abrasion Tearing Wear recovery recovery resistance strength rating (percent) (percent) (times) (kg (grade) Example 14:

as 07 an 0.81 4' 65 65 387 0.74

65 63 338 0.68 5 F 65 61 281 0.55 Example 23, control:

Whichever method of curing is applied the limitation that the amount of catalyst be from 5 to 20% by weight is critical.

The reason for this limitation is as follows:

The lower limit of 5% is a value above which conspicuous improvements in W.C.R. and W. & W. are attained as shown in the following Example 24. The upper limit of 20% is based on reasons which have no direct connection with the effects obtained in the treated fabrics. That is, even when the amount of the catalyst exceeds 20%, the same effects as those obtained using the catalyst in an amount within the limited range are obtained. However, when the amount exceeds 2.0% the time stability of the bath is lowered. For example, when weight percent of dimethylol hydroxyethylene u-rea solution is used as the bath and weight percent of NH Cl is contained therein, the pot life of the bath is 8l0 hours, while with weight percent of NHgCl, the pot life is at most 5 hours. The pot life is referred to at room temperature, but it has an important meaning in the industrial working production.

The data in Example 24 shows the relation between the addition amount (OWF) of NH Cl and the finishing effects using dimethylol hydroxyethylene urea as a cross linking agent. This data will sufficiently show the criticality of the amount of the catalyst.

EXAMPLE 24 Plain fabrics made of cupra (cuprammonium rayon) filament yarns (W. 60 den. F. 75 den.) were padded in a solution containing 15% by Weight of dimethylol hydroxyethylene urea, and NH Cl of varying concentrations.

The amount of pick up was 90%. The padded fabrics were then allowed to stand for 3 hours to reach a state of moisture equilibrium at room temperature in a closed chamber, and subjected to curing at 130 C. for one minute by introducing same into a contactly closed heating passage.

The heating passage was formed between a heated cylinder and a silicon rubber belt which was hung around the cylinder under tension. The rubber belt was moved at the same speed as the peripherial speed at which the heated cylinder was rotated.

The cured fabrics were then soaped and tentered. The properties of the resulting fabric are as shown in Table 8.

TABLE 8 Cone. of Properties FA W. & W. NHrCl obtained DOP WO R (times) TS rating {F 52 53 410 0. s i 4 5 {W 70 66 458 0.9 5

a 69 6; Big 8 72 6 5 .9 71 05 43 3.7 i 5 101 70 70 5 .9

a a a 8-5 20.

O {F s5 68 305 0.6 i 5 Nora-Measuring conditions and symbols are as defined above in the original text.

What is claimed is:

'1. A method for providing cellulosic fabrics with crease resistance and a high wash and wear rating, said method comprising padding the fabric in a solution to provide on the fabric 5 to 15% of an aminoplast cellulose reactant type cross-linking agent and 5 to 20% of a catalyst which is ammonium chloride or ammonium nitrate, the percent being based on the weight of cellulose in the fabric and curing the padded fabrics at a temperature of to C. for 1 to 8 minutes in an atmosphere containing 20 to 100% by volume of moisture.

2. A method for providing cellulosic fabrics with crease resistance and a high wash and wear rating, said method comprising padding the fabric in a solution to provide on the fabric to of an aminoplast cellulose reactant type cross-linking agent and 5 to of a catalyst which is ammonium chloride or ammonium nitrate, the percent being based on the weight of cellulose in the fabric and curing the padded fabrics at a moisture content of 12-25% of the fabric at a temperature of to C. by holding said padded fabrics between two moving members which are impermeable to steam and which form a contactly closed heating passage.

3. A method according to claim 1 wherein the cellulose reactant type cross-linking agent is dimethylol hydroxyethylene urea.

4. A method according to claim 1 wherein the cellulose reactant type cross-linking agent is tetramethylol acetylene di-urea.

5. -A method according to claim 2 wherein the cellulose reactant type cross-linking agent is dimethylol hydroxyethylene urea.

6. A method according to claim 2 wherein the cellulose reactant type cross-linking agent is tetramethylol acetylene di-urea.

References Cited UNITED STATES PATENTS 3,177,096 4/1965 Van Loo et al. 8116.3 X 2,899,263 8/1959 Nucssle et a]. 8-116. 3 3,220,869 11/1965 Ruemens et al. 8l16.3 X 3,135,710 6 1964 De Bonneville 8116.3 X 2,820,715 1/1958 Brookes et al. 8-1163 X GEORGE F. LESM-ES, Primary Examiner H. WOIJMAN, Assistant Examiner U.S. Cl. X.R. 

